"How stupid can you get?" Joan asked when I talked to her on Monday. "Christina must have been thinking about food, that's why she forgot the words."

Before the big game, Christina belted out "What so proudly we watched at the twilight's last reaming" instead of "O'er the ramparts we watch'd, were so gallantly streaming." It was the second time she sang the "What so proudly" line, but before she used the word "gleaming" instead of "reaming."

The 'Joan & Melissa: Joan Knows Best?' star continued using Christina's oft-fluctuating weight to rough up Christina, and offered a line she thought she could have used, "O say can you see ... french fries." Joan snarked that there was an upside to Christina's fluctuating weight. "She's gotten so big," -- here's where you say how big is she? -- "She looks like she could eat Lady Gaga. Great way to get rid of competition."

After 'The Star-Spangled Banner' wrapped, Aguilera headed backstage where a source told me that the singer was "devastated" by her mistake.

Aguilera addressed her performance in a statement to the press. "I got so caught up in the moment of the song that I lost my place. I can only hope that everyone could feel my love for this country and that the true spirit of its anthem still came through."

Joan made her own appearance during the Super Bowl as well. She's the new Go Daddy girl and starred in their big ad this year. Jillian Michaels and Danica Patrick spend the :30 ad introducing their newest model, but you don't catch a glimse of her face until the last second.

"They were looking for someone stupid to be their new spokesperson," she tells me. "I'm now Joan.co. It couldn't be any easier."

Though she's joked on Twitter that it was actually her 77-year-old body in the ad, the buxom figure reportedly belongs to model Tabitha Taylor, who starred in a popular Go Daddy ad for the 2009 Super Bowl.

PopEater got the word on the street about Christina's Super Bowl performance -- check it out:

Seriously, it was an honest mistake, made by others before her! Not an act of treason for God's sake!!! Joan Rivers? Such a joke she is herself...at one time she was funny, now she is just mean and hateful. Her face is getting REALLY scary. Go get something lifted!!!

No that definitely is NOT JR's body. That picture screams touch-up!! She's got some nerve talking about Christina's weight when she feels so bad about her own looks she has her face sliced up and stretched so tight she looks like someone squeezed her head. ROFL!!

Xtina is a bloated drunk with Rickets! A flop with everything she does with her 20 tons of pasty clown makeup and her screwed up head strolling around with that so-called boyfriend who is nothing but her beard. Jordan has already spilled the beans about this Lesbo drunk!

I'm with Jay. Something that really peeves me is when someone sings the National Anthem and trys to "make it their own". This song belongs to every American, and all the flourishes and rifts just means no one else can sing along, if they want to. Just sing the song.

This loud mouth over-rated plastic surgery queen needs a good as...whipping. She sits on TV picking on others's when her faults are many. Her and that clone daughter of hers. ICK! I'd like to see you sing it you, bleep, bleep, bleep.